This section provides background information related to the present disclosure which is not necessarily prior art.
A fuel cell generates electricity using a principle of taking electricity during the process of obtaining water from a reaction of hydrogen and oxygen (air). This fuel cell includes a fuel cell stack including a plurality of layers of cells each made up of: an electrolyte membrane letting hydrogen ions pass therethrough; and two separators sandwiching the electrolyte membrane therebetween. The separators forming a cell are required to have a sealing property to block hydrogen and oxygen and a conductive property enabling electricity to be taken.
Since hydrogen, oxygen, strong acids, hydrofluoric acids, coolant water and the like are used in the stack, a gasket is incorporated therein so as to seal these substances. The gasket has to deal with such various sealing objects including hydrogen, oxygen, strong acids, hydrofluoric acids and coolant water, and an adhesive also is required to be resistant to these sealing objects.
The gasket has to have durability for a very long time, and the adhesive also is required to keep attachability over a long time period, i.e. to have durable strength. Deterioration in the attachability causes a problem of gasket displacement due to a pressure in the cell, for example.
Meanwhile, as illustrated in FIG. 4, a fuel cell constituting component is known, which is obtained by applying an adhesive 3 on the entire bottom surface of a gasket 1 so as to chemically bond an attachment member 5 such as an impregnation integral molding carbon plate, a metal plate, or a resin film, thus integrating the attachment member 5 and the gasket 1.
As illustrated in FIG. 5, however, when the adhesive 3 is applied on the entire surface, a sealing object S on a stack inside A might enter into an interface between the gasket 1 and the attachment member 5, and cleave chemical bonding between rubber and the adhesive, and such deterioration might diffusively spread so as to attack the continuous adhesive application layer progressively, thus leading to an increasing tendency of deterioration in attachability.
Further, as illustrated in FIG. 6, there is another problem that the adhesive interface undergoes a force similar to stress generated at the bottom surface of the gasket 1 during compression of the gasket 1, so that a load is generated upon bonding the gasket 1 to the adhesive 3. This might lead to not only the deterioration in attachability but also a reason for rupture H of the gasket 1 itself as illustrated in FIG. 7.